Best time to visit
June to August are particularly suitable for summer activities. The weather is just not always stable. The months of December to March are best for winter sports. City trips are possible all year round, although cities such as Zurich and Geneva are particularly beautiful in summer.
Driving
A national driving license is sufficient for EU citizens. The road network is well developed and the roads are in good condition. The traffic signs and rules are mostly standardized within Europe.
The speed limits are 120 km/h on freeways, 100 km/h on highways, 80 km/h outside built-up areas and 50 km/h within built-up areas. You need a vignette for the highway. This costs CHF 40 per calendar year.
During the day, you must drive with daytime running lights or dipped headlights. The blood alcohol limit is 0.5 per mille. You should adhere to all regulations if you do not want to pay expensive fines.
You can find more information here.
Phone
Depending on your phone provider, you may not pay roaming charges if you have a phone contract from the EU or the Schengen area. You can then use your phone at the same rate as at home. If this is not the case with your phone provider, you can get an international SIM card if the Wi-Fi in your accommodation, restaurants or public places is not enough for you. I can recommend Airalo for this.